Sialadenoma Papilliferum: Analysis of Seven New Cases and Review of the Literature

Abstract

Sialadenoma papilliferum (SP) is a rare benign salivary gland neoplasm that comprises from 0.4 to 1.2% of all salivary gland tumors. The tumor is so named because of its microscopic resemblance to the syringocystadenoma papilliferum, an uncommon benign tumor of sweat gland origin. The purpose of this paper is to report the clinical and microscopic features of seven new cases of SP and combine them with cases previously reported in the English language literature to further define this unusual lesion. Combining our cases with acceptable cases from the literature, the palate (especially the hard palate) was the most common site, with 80% of the cases occurring in this location. Other locations in decreasing order were buccal mucosa, upper lip, retromolar pad, and parotid gland. Age at diagnosis ranged from 18 to 87 years with a peak in the 6th decade and an average age of 56.4 years. Microscopically, the lesions demonstrated a papillary surface morphology, and the papillary projections varied from long and pointed to short and blunted. The supporting connective tissue contained a variable number of convoluted ductal structures, which often fused with the overlying surface epithelium. The ductal structures exhibited papillary infoldings and were lined by a double layer of epithelium consisting of basal cell layer and a luminal layer of cuboidal-to-columnar ductal cells. Immunohistochemical reactivity with p63 and p40 indicated that the basal cell layer was comprised predominantly of neoplastic myoepithelial cells. The luminal cells were immunoreactive with epithelial membrane antigen characteristic of ductal cell differentiation. Conservative surgical treatment was accomplished in most cases and appears to be adequate treatment as only two recurrences were documented. Several case reports of purported malignant transformation in SP have been reported in the literature, but in our opinion, there is insufficient evidence in the publications to unequivocally determine whether any of the malignancies truly originated within a pre-existing SP.

Histopathological evaluation of minor salivary gland papillary–cystic tumours: focus on genetic alterations in sialadenoma papilliferum and intraductal papillary mucinous neoplasm

“…The histological origin and tumorigenesis of SP have been long debated and remain to be elucidated . In earlier descriptions the possibility of a metaplastic or reactive process was suggested .…”

“…performed a retrospective search to identify institutional and consultation cases with an initial diagnosis of ‘SP’, ‘intraductal papilloma’, ‘cystadenoma’, ‘cystadenocarcinoma’, or miscellaneous papillary–cystic tumour of the minor salivary glands, and retrieved a total of 28 cases. Histological diagnoses were made on the basis of the 2017 World Health Organization (WHO) classification of head and neck tumours and related previous studies . After re‐evaluation, the cases were reclassified as follows: SP ( n = 10), SP‐like intraductal papillary tumour (SP‐IPT) ( n = 2), IPMN ( n = 9), intraductal papilloma ( n = 2), cystadenoma ( n = 3), and cystadenocarcinoma ( n = 2).…”

A Rare Case of Intraductal Papilloma Arising from Minor Salivary Gland in the Floor of the Mouth

“…Additionally, sialadenoma papilliferum is characterized by a combination of exophytic projection of the surface squamous epithelium and inward papillary proliferation of duct epithelial cells [ 1 , 2 , 6 , 7 ]. The underlying glandular component forms papillary extensions surfaced by columnar or cuboidal cells or both, which is contiguous with underlying arborizing ductal structures and cystic spaces.…”

Analysis of the Clinical Relevance of Histological Classification of Benign Epithelial Salivary Gland Tumours

“…Approximately 80% of cases occur in the palate (particularly the hard palate), others in decreasing order in the buccal mucosa, upper lip, retromolar pad, and parotid gland, but cases have also been reported in the bronchus and nasopharynx [53,54]. The peak age is in the 6th decade [55]. SP was first described by Abrams and Finck in 1969 [56] and presents clinically as a painless exophytic papillary mass, often misinterpreted clinically as squamous cell papilloma, warty dyskeratoma or verrucous carcinoma [57].…”

“…SP was first described by Abrams and Finck in 1969 [56] and presents clinically as a painless exophytic papillary mass, often misinterpreted clinically as squamous cell papilloma, warty dyskeratoma or verrucous carcinoma [57]. A literature review in 2007 by Mahajan et al [58] found a total of only 47 reported cases, a number that has increased substantially following the 7 new cases reported by 2018 [55].…”